Find X,Y coordinate of a text character?

While the Active System Box (ASB) doesn't have an innate way to do this, does anyone have any sort of creative ideas for finding the X position of the right edge of a specific character within the ASB? The Calc Text Rect is useful for this but includes a fair bit of font padding at times, which is rendered at different sizes on different exports/browsers/operating systems.

Even if I could just routinely find the X position or the next character in a string, I could accomplish what I'm after.